Aqueous cooling systems are subjected to stress during their operation. Many aqueous cooling systems employ a cooling tower that allows heat to dissipate from the cooling water via evaporation. A typical stress to the aqueous cooling system involves mineral scale buildup in the cooling tower, thereby decreasing the efficiency of the cooling tower and aqueous cooling system. Specifically, as the heat in an aqueous cooling system dissipates via evaporation, the components of mineral scale in the remaining water become more concentrated, causing precipitation of the mineral scale on the internals of the cooling tower, and thereby creating operational problems and/or decreased efficiency. Parameters known to typically influence scaling include concentration of scaling species, pH, temperature, flow rate, and concentration of scale-inhibiting chemicals present in the cooling water. Unlike most dissolved species, the solubility of scaling species found in cooling water is typically inversely proportional with temperature (i.e., higher cooling water temperature leads to more scaling). When the aqueous cooling system increases cycles, the concentration of ions such as Ca and Mg increases. To combat this stress the aqueous cooling system is typically blown down and makeup water is added into the system, thereby exchanging a portion of the cooling water for makeup water that is more pure.
Various types of monitoring systems have been used with aqueous cooling systems including those utilizing conductivity meters, and those incorporating fluorometric monitoring and control of treatment chemicals. Piezoelectric microbalance sensors have been utilized in several applications. U.S. Pat. No. 6,250,140 to Kouznetsov et al., the disclosure of which is herein incorporated by reference in its entirety, describes a quartz crystal microbalance device. U.S. Pat. No. 6,143,800 to Nguyen et al.; U.S. Pat. No. 6,375,829 to Shevchenko et al.; U.S. Pat. No. 6,942,782 to Shevchenko et al.; U.S. Pat. No. 7,842,165 to Shevchenko et al.; U.S. Pat. No. 5,734,098 to Kraus et al.; U.S. Patent Application Publication Nos. 2006/0281191 to Duggirala et al. and 2012/0073775 to Duggirala et al. describe quartz crystal microbalance devices and applications.